The present invention relates to a portable electronic device and its secret information collation method, and in particular to a secret information collation scheme for IC card data processing system in which it is hard to perform illegal access from the readout terminal side and security of IC cards can be improved.
In a conventional information processing system using IC cards or the like as described in JP-A-52-7646, for example, secret information such as a secret identification number is collated at the IC card side in response to a directive given from the terminal side. Upon coincidence, access to a memory contained in the IC card is permitted and transactions processing can be continued. When the results in the above described collation is noncoincidence, the number of times of noncoincidence is administered. If the number of times of error reaches a predetermined number or more, the illegal IC card is excluded. By doing so, illegal use of an IC card caused by forgery or fraud is prevented.